Electric motor frame construction



Feb. 21, 1950 w. J. BAUROTH ELECTRIC MOTOR FRAME CONSTRUCTION Filed Sept. 11, 1947 WALTER J. BAu ROTH,

Patented Feb. 21, 1950 UNITED ELECTRIC MOTOR FRAME CONSTRUCTION Walter J. Bauroth, Columbus, Ohio, assignor to The Jeffrey Manufacturing Company, a corporation of Ohio Application September 11, 1947, Serial No. 773,336

6 Claims. 1

This invention relates to an electric motor and particularly to improved construction of the frame of an electric motor which has one or more relatively thin walls to provide a minimum dimension, in which supplemental magnetic flux carrying ribs or paths are provided to supplement the thin walls which are of magnetic material and provide a flux path, to the end that the magnetic path of the flux will not be saturated.

Other objects of the invention will appear hereinafter, the novel features and combinations being set forth in the appended claims.

In the accompanying drawings,

Fig. 1 is a combination elevational and sectional view of a mining machine which incorporates an electric motor having the features of my invention; and

Fig. 2 is a sectional view taken on the line 22 of Fig. 1, looking in the direction of the arrows.

The mining machine which is illustrated in part in the drawings is disclosed in full detail and claimed in the application of Arthur L. Lee, Serial No. 586,979, filed April 6, 1945. Certain features herein disclosed are claimed in said Lee application or one or more divisions thereof. This includes all novel features not herein claimed, including the general structure of the motor. ignoring the ribs which provide greater magnetic area, with the inclined lateral poles, and the frame structure providing the paths for the cutter chain, among other features.

One of the problems which is constantly encountered in mining machinery, of which the socalled Shortwall mining machine is an extreme illustration, is that of providing a minimum dimension, such as a minimum height, to the end that the machine may be used in very low coal vein seams. The problem which this invention solves was created by producing a very'low height mining machine, as disclosed in the Lee applica tion above identified.

The motor I54 disclosed includes a frame 4| of magnetic material, such as iron, which is the frame not only of the mining machine but also of the electric motor thereof, said electric motor I54 including an armature or rotor I55 which is mounted upon a hollow tube or shaft I56 coupled to a drive shaft through a clutch, not illustrated, having a lubricating bore I52 therethrough. The armature I55 is provided with the usual armature windings and commutator and the body of it is of laminated iron or steel, providing indicated paths for the magnetic flux which is developed by the field structure and which flows through the main frame 4I. .On the front of the main frame M is a removable plate ISI which in turn' carries a clutch casing Il'i having at its center a removable bearing plate I18.

Adjacent the bottom of the main frame 4| there is a pair of laterally spaced arms E89 which cooperate to form a groove 20'! along each side of the main frame adjacent a lateral passageway 208 for an endless cutter chain 46 having fanned bits 41 which pass through the passageways 206 as the cutter chain 45 is driven by the electric motor I54, hereinafter described in detail, to cut a kerf in a manner disclosed in detail in the Lee application above identified. The outer perimeter of each passageway 205 is defined by a rib I4l forming an integral part of the main frame 4| In Fig. l of the drawings there are also shown some incidental features of the mining machine which are disclosed and claimed in the Lee application above identifled, including a leveling piston motor or jack 58 having a foot pad I43 and including a sheave assembly 55 which includes a pivoted sheave plate or bracket I provided with a central pin or post I88 and carrying a sheave H31, the assembly being releasably latched by a latch I88.

Other incidentally disclosed features include a screw I cooperating with an ear I94, there being one for each arm I89 by which it is attached to the main frame 4!. Also there are removable guides or wear strips 298 and 209 adjacent the grooves 281.

Referring more particularly to other features of the electric motor which are significant parts of the instant application, the main frame 4| is provided with a pair of similarly located main poles on opposite sides of the longitudinal axis thereof, one of which is seen at 20!! and upon which there is an energizing winding I99. The pole 280 is provided with a pole shoe I98 which is located adjacent the periphery of the armature 155. Pole shoe I98 and pole 280 are removably attached to the main frame 4! by one or more through bolts 2!.

The electric motor I54 illustrated is of the consequent pole type which is a feature contributing toward its low overall height, the consequent poles being located at the top and bottom of the motor, with the main or salient poles extending laterally or to the sides. Two consequent poles are seen in Fig. l of the drawings, being provided respectively with pole shoes I96 and I9! removably attached to the main frame M. A compensating interpole 2. 32 is likewise attached to the main frame 4! by screws 2% and is provided with a compensating coil or winding 2M, the pole face projecting in a position adjacent the armature I55.

By reference to Figs. 1 and 2 of the drawings it will be seen that there are two walls of the main frame, casing or housing 4| of the electric motor and mining machine which have a restricted dimension. In other words, they should be as thin, as possible. For example, the top wall of said main frame 4| is made quite thin. Likewise the wall which forms the top of the passageway 206 is made quite thin. For structural purposes it is entirely permissible tomakethe top and bottom walls, as seen in Fig.2 of the drawings, with a dimension not greaterthan the minimum dimension there shown. Whilethisis entirely adequate for structural purposes it is inadequate for magnetic purposes since thepaths for the magnetic flux induced by the energizing winding I99 will pass through branches,one of which is through the lower wall, as viewed in Fig. '2, and the other through the upper wall, as thererviewed, passing through the iron of the main frame 4| and through the consequent'poles I96, l91and the iron of the armature 155, as illustrated by the. arrows in Fig. 1 of the drawings.

Inorder to make up for what otherwise would bea deficiency in cross-sectional area of the magnetic path for the flux developed by the winding-199 and thus to prevent saturation ofthe iron of said magnetic path with 'a consequent lowering of the energy which them-otor could develop, I have provided means to build up the cross-sectional area ofthe magnetic path adjacent the otherwise deficient thin wall areas of the motor, by providing supplemental flux carrying ribs ;or projectionsr2fl5 which are formed as integral parts of the main frame 4i. These ribs or projections extend along the adjacent wall surface and. are integrally formed therewith. Furthermore, they :projectinwardly of the casing or main frame walls in-areas whichare other-- wisehunusedrthus not interfering with any normal mechanism and not :in any way increasing a vital dimension .of the motor or mining machine.

As. illustrated, the ribsor projections 205 :are adjacent and substantially/parallel with "the coil l;99,Ither-e being a rib on each side thereof, particularly adjacent the thin wall whichforms the top of-the passageway 2116. Likewise, adjacent the top wall of the main frame 4|, the mainpor- 1 tion l-of which is -thin,@there are ribs "2-835 which also extend laterally on opposite sides of the interpole coil or win-dingZM which is also somewhat :in a position-adjacent and above the main or salient pole '200 and substantially parallel therewith. It is .to be noted that the top wall of casing 44 and *the lower wall which formsthe topof passageway 2-116 cooperate to shroud the pole 29d and its winding 199. The added crossseetiona-l area at the critical positions in the magnetic path provided by the main frame '44 produced by the ribs or projections -2ll5iis sufficient to prevent saturation of the iron or magneticmater-ial atany position in its path. Stated in broaderterms, the pole 200 and winding E89 arepositioned between two thin opposite walls, formingpart of the magnetic path of said pole, the. outer surfaces of which walls aredesirably spaced apart a limited or restricted distance along onedimensional axis perpendicular to the longitudinal axis of said pole. Said limited dimensional axis is also at right angles to at least one of said thin walls. To compensate ma n t ca o t thinn s o said opposite walls, ribs 205 are provided inside said walls and laterally of said coil I99 and pole 200 relative to said restricted dimensional axis. Said ribs 205 project inwardly or at right angles to the plane of the attached thin wall.

As a consequence of the above provision it is possible to construct a mining machine in which the main portion'of the main frame housing, which carries the'magnetic flux, has -a crosssectional area below that required to carry the flux without saturation, the flux saturation being prevented. by, the building up of said crosssectional area at its normally deficient places by fiuxconducting ribs or projections.

,Obviously:those skilled in the art may make various changes in the details and arrangement of parts without departing from the spirit and scope of the invention as defined by the claims .heretoappended, and I therefore wish not to be restricted to the precise construction herein disclosed.

Having thus shown an embodiment of my invention, what I desireto secure by. Letters Patent of the United States is:

1. An electric :motor including-a .main frame,

a field pole magnetically connected to said main frame,an energizing windingvfor saidfield pole, an armature-adjacent said field pole, said armature, field pole and main frameall containing magnetic material and providing a path for magnetic flux induced 'by said energizing winding, said main frame :having walls on opposite sides of said pole and winding, eachhaving a relatively smallcross-sectional area adjacentand substantially-parallel said 'field coil on opposite sides magnetic zmaterial: in. :said fiux path to :preventfi;

said tendency to saturate.

2. An electric .motor including a main frame, a field pole magnetically connected to said main frame, an energizing winding for said field pole, anarmature adjacent said field pole, said armature field pole and mainframe all containing magneticmaterialand providing a path for magnetic flux induced by said energizing winding, said main frame having :a wall of relatively small cross-sectional dimension perpendicular to a restricted dimensional axis producing a crosssectional areais inadequate to carry the magnetic flux developed by said winding without tending to saturate :it'magnetically, and means including aprojecting'rib of magnetic material added to said :frame 'aati saidarea of relatively small cross-sectional :area and projecting inwardly fromsaid :wall iand'lccated laterally of said pole, toi'provide :adequate total cross-sectional :area of :magnetic material in said flux path to prevent. said tendency to saturate.

3. An'electric'motor including an enclosing main framehousing having a thin wall to produce alow dimension of saidframe, aroto'r in said frame, a magnetic field pole attached'to said frame-and having a face adjacent said rotor,

an energizing windingifor'said pole, said thin wall of said main frame, said pole and said rotor being of magnetic material and providing a path for magnetic flux induced by said energizing winding, and means including a rib of magnetic material formed adjacent said thin wall and integral therewith along one side and laterally of said pole and projecting at right angles to the plane of said thin wall and operative to increase the effective cross-sectional area of the magnetic path adjacent said thin wall.

4. A mining machine including an electric motor having a minimum height, said motor including an enclosing main frame housing having a thin top wall to produce a low dimension of said frame, a rotor in said frame, a magnetic field pole attached to said frame and extending laterally inwardly from said frame and having a face adjacent said rotor, an energizing winding for said pole, a thin wall of said main frame below said winding providing the top of a cutter chain passageway in said main frame housing, said top and lower thin walls shrouding said pole and its energizing winding, said thin walls of said main frame, said pole and said rotor being of magnetic material and providing a path for magnetic flux induced by said energizing winding, and ribs of magnetic material formed adjacent said thin walls and integral therewith along one side and along the sides of said winding and extending inside said thin walls and laterally of said pole and winding relative to an axis designating the thin wall dimensions of magnetic material on opposite sides of said pole, said ribs being operative to increase the effective crosssectional area of the magnetic path adjacent said thin walls.

5. A low height mining machine including a main frame, an electric motor in said frame including a rotor, inwardly and laterally extending poles attached at opposite sides of said main frame and having faces adjacent said rotor, said main frame cooperating with said poles and rotor to provide a magnetic path, said main frame having top and bottom walls adjacent said poles and cooperating with said frame to shroud said poles and being thin and of low cross-sectional area which is inadequate to carry the desired flux without saturation, the bottom walls below said poles cooperating with other frame parts to provide a path for a cutter chain the opposite runs of which are above the bottom extremity of said main frame, and ribs of magnetic material carried on and inwardly of said top and bottom thin walls adjacent and substantially parallel with said poles and laterally of the poles and windings along the thin wall axis to increase the effective crosssectional area of the magnetic path adjacent said thin walls.

6. A low height mining machine including a main frame, an electric motor in said frame including a rotor, inwardly and laterally extending poles attached at opposite sides of said main frame and having faces adjacent said rotor, said main frame cooperating with said poles and rotor to provide a magnetic path, said main frame having bottom walls adjacent said poles and cooperating with said frame to shroud said poles and being thin and of low cross-sectional area which is inadequate to carry the desired flux without saturation, the bottom walls below said poles cooperating with other frame parts to provide a path for a cutter chain the opposite runs of which are above the bottom extremity of said main frame, and ribs of magnetic material carried on said bottom thin walls and inwardly of said frame and adjacent and substantially parallel with said poles and laterally of the poles and magnetic windings along the thin wall axis to increase the eifective cross-sectional area of the magnetic path adjacent said thin walls.

WALTER J. BAUROTH.

REFERENQES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 839,502 Meyrs Dec. 25, 1906 910,892 Bary Jan. 26, 1909 1,404,306 Levin Jan. 24, 1922 2,075,870 Sloane Apr. 6, 1937 OTHER REFERENCES Die Gleichstrom Machine, Arnold, vol. II, page 119, Springer, Berlin, 1907. 

